I personally think GT5:P is a great game and GT5 is probably going to be the best for a long time, but just for fun, comments or things to be added or improved in the full version. Apart from the obvious stuff, like improved online playing, damage, etc.
I personally would like the option for the controller to be mapped directly to the steering, not like it is now since with a controller if you steer at the max, the game decides how much to steer.
Also there are some things that are completely black just because they are not directly light up by the sun, like somethings the steering wheel etc, completely black.
The dust and smoke made by the tires either when spinning or going off on the grass, goes away immediately, so if they could just let it dissolve for a couple extra seconds to look more realistic
(Although these last two are probably too hard on the ps3)
Just anything you'd like changed, anything be harsh
I'm kind of a noob when it comes to the GT games because I only own GT3 apex and have tried GT5:P. The main thing I was let down on was the lack of car performance customization like GT3 had, like buying flywheels, turbos, suspension etc. I haven't beaten GT5:5 completely so if it is in there my bad, but if not I'd really like to see it in GT5:P.